<!doctype html>
<html>

<head>
    <title>Pie Chart</title>
    <script src="../dist/Chart.bundle.js"></script>
    <script src="http://cdnjs.cloudflare.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>
</head>

<body>
    <div id="canvas-holder" style="width:50%">
        <canvas id="chart-area" width="300" height="300" />
    </div>
    <button id="randomizeData">Randomize Data</button>
    <button id="addDataset">Add Dataset</button>
    <button id="removeDataset">Remove Dataset</button>
    <script>
    var randomScalingFactor = function() {
        return Math.round(Math.random() * 100);
    };
    var randomColorFactor = function() {
        return Math.round(Math.random() * 255);
    };
    var randomColor = function(opacity) {
        return 'rgba(' + randomColorFactor() + ',' + randomColorFactor() + ',' + randomColorFactor() + ',' + (opacity || '.3') + ')';
    };

    var config = {
        type: 'pie',
        data: {
            datasets: [{
                data: [
                    randomScalingFactor(),
                    randomScalingFactor(),
                    randomScalingFactor(),
                    randomScalingFactor(),
                    randomScalingFactor(),
                ],
                backgroundColor: [
                    "#F7464A",
                    "#46BFBD",
                    "#FDB45C",
                    "#949FB1",
                    "#4D5360",
                ],
            }, {
                data: [
                    randomScalingFactor(),
                    randomScalingFactor(),
                    randomScalingFactor(),
                    randomScalingFactor(),
                    randomScalingFactor(),
                ],
                backgroundColor: [
                    "#F7464A",
                    "#46BFBD",
                    "#FDB45C",
                    "#949FB1",
                    "#4D5360",
                ],
            }, {
                data: [
                    randomScalingFactor(),
                    randomScalingFactor(),
                    randomScalingFactor(),
                    randomScalingFactor(),
                    randomScalingFactor(),
                ],
                backgroundColor: [
                    "#F7464A",
                    "#46BFBD",
                    "#FDB45C",
                    "#949FB1",
                    "#4D5360",
                ],
            }],
            labels: [
                "Red",
                "Green",
                "Yellow",
                "Grey",
                "Dark Grey"
            ]
        },
        options: {
            responsive: true
        }
    };

    window.onload = function() {
        var ctx = document.getElementById("chart-area").getContext("2d");
        window.myPie = new Chart(ctx, config);
    };

    $('#randomizeData').click(function() {
        $.each(config.data.datasets, function(i, piece) {
            $.each(piece.data, function(j, value) {
                config.data.datasets[i].data[j] = randomScalingFactor();
                config.data.datasets[i].backgroundColor[j] = randomColor(0.7);
            });
        });
        window.myPie.update();
    });

    $('#addDataset').click(function() {
        var newDataset = {
            backgroundColor: [randomColor(0.7), randomColor(0.7), randomColor(0.7), randomColor(0.7), randomColor(0.7)],
            data: [randomScalingFactor(), randomScalingFactor(), randomScalingFactor(), randomScalingFactor(), randomScalingFactor()]
        };

        config.data.datasets.push(newDataset);
        window.myPie.update();
    });

    $('#removeDataset').click(function() {
        config.data.datasets.splice(0, 1);
        window.myPie.update();
    });
    </script>
</body>

</html>
